Re: [PATCH] firmware, memmap: fix firmware_map_entry leak

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

On Mon, Apr 15, 2013 at 02:48:17PM +0900, Yasuaki Ishimatsu wrote:
>When hot removing a memory, a firmware_map_entry which has memory range
>of the memory is released by release_firmware_map_entry(). If the entry
>is allocated by bootmem, release_firmware_map_entry() adds the entry to
>map_entires_bootmem list when firmware_map_find_entry() finds the entry
>from map_entries list. But firmware_map_find_entry never find the entry
>sicne map_entires list does not have the entry. So the entry just leaks.
>
>Here are steps of leaking firmware_map_entry:
>firmware_map_remove()
>-> firmware_map_find_entry()
>   Find released entry from map_entries list
>-> firmware_map_remove_entry()
>   Delete the entry from map_entries list
>-> remove_sysfs_fw_map_entry()
>   ...
>   -> release_firmware_map_entry()
>      -> firmware_map_find_entry()
>         Find the entry from map_entries list but the entry has been
>         deleted from map_entries list. So the entry is not added
>         to map_entries_bootmem. Thus the entry leaks
>
>release_firmware_map_entry() should not call firmware_map_find_entry()
>since releaed entry has been deleted from map_entries list.
>So the patch delete firmware_map_find_entry() from releae_firmware_map_entry()
>

Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>

>Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>---
> drivers/firmware/memmap.c |    9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
>diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
>index 0b5b5f6..e2e04b0 100644
>--- a/drivers/firmware/memmap.c
>+++ b/drivers/firmware/memmap.c
>@@ -114,12 +114,9 @@ static void __meminit release_firmware_map_entry(struct kobject *kobj)
> 		 * map_entries_bootmem here, and deleted from &map_entries in
> 		 * firmware_map_remove_entry().
> 		 */
>-		if (firmware_map_find_entry(entry->start, entry->end,
>-		    entry->type)) {
>-			spin_lock(&map_entries_bootmem_lock);
>-			list_add(&entry->list, &map_entries_bootmem);
>-			spin_unlock(&map_entries_bootmem_lock);
>-		}
>+		spin_lock(&map_entries_bootmem_lock);
>+		list_add(&entry->list, &map_entries_bootmem);
>+		spin_unlock(&map_entries_bootmem_lock);
>
> 		return;
> 	}
>
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